Magnesium and Cortisol: What the Research Says
Magnesium is one of the most recommended supplements for stress online, often with the promise that it "lowers cortisol." The research is much thinner than that. There's some evidence for magnesium and feelings of anxiety, but it's weak. Direct evidence that magnesium lowers cortisol is thinner still.
Here's what the studies show. We don't give doses here. If you're thinking about a supplement, talk to a doctor or pharmacist first.
This article is for general information and isn't medical advice.
Does magnesium lower cortisol?
We didn't find a systematic review or meta-analysis showing that magnesium supplements lower cortisol in the blood. The most direct trial we found was a post-hoc analysis (a second look at data from a trial designed for another question). In 49 overweight adults aged 45 to 70, 24 weeks of magnesium was linked with lower cortisol in 24-hour urine samples compared with placebo (Schutten et al., 2021). That's one small study, it wasn't designed to test cortisol, and it doesn't tell us whether people felt any different.
Magnesium and stress or anxiety
A 2017 systematic review looked at 18 studies of magnesium and anxiety or stress. The authors concluded that the evidence is suggestive of a benefit for anxiety, but that its quality is poor. All of the studies recruited people who were already vulnerable to anxiety, such as people with mild anxiety or premenstrual symptoms (Boyle et al., 2017). The authors called for better-designed trials.
What the research says, at a glance
| Claim | What the research shows | How strong |
|---|---|---|
| Magnesium lowers cortisol | One small post-hoc analysis found lower urinary cortisol over 24 weeks (Schutten et al., 2021) | Weak |
| Magnesium eases anxiety | A review of 18 studies found suggestive evidence of poor quality (Boyle et al., 2017) | Weak |
| Magnesium helps everyone under stress | Studies only included people already prone to anxiety | Not shown |
Food first
Magnesium is in many everyday foods, including legumes, nuts, seeds, whole grains and green leafy vegetables (NIH Office of Dietary Supplements). A varied diet is a reasonable way to get it without guessing at supplement amounts. The balanced-plate guide in The Cortisol Paradox (protein, colorful vegetables, slow carbs and healthy fats) is one way to build meals like that. See the balanced-plate part of the 21-day routine.
For how food in general relates to cortisol, see food and cortisol. For other supplements sold for stress, see cortisol supplements: an evidence check.
Safety
The NIH notes that magnesium from supplements, unlike magnesium from food, can cause diarrhea, nausea and cramping at high intakes. It can also interact with some medicines, such as bisphosphonates for osteoporosis (NIH Office of Dietary Supplements). Check with a doctor or pharmacist before taking it.
When to see a doctor
Talk to a doctor if:
- You feel anxious or stressed most days for two weeks or more.
- You're thinking about taking magnesium and you take other medicines or have kidney problems.
- You're pregnant or breastfeeding.
- You have symptoms you think are caused by cortisol. A doctor can test for this properly.
FAQ
Does magnesium lower cortisol?
There isn't good evidence that it does. One small analysis found lower urinary cortisol, but no pooled review has shown an effect.
Is magnesium good for stress?
A review found suggestive but poor-quality evidence for anxiety, mainly in people already prone to it. Better trials are needed.
Should I take magnesium for cortisol?
That's a question for your doctor or pharmacist, especially if you take other medicines. Getting magnesium from food is a low-risk starting point.
The short version
The claim that magnesium lowers cortisol rests on very little evidence. There's weak, suggestive evidence for anxiety. If you're considering a supplement, ask a doctor or pharmacist first, and for the bigger picture see wired but tired.
Last reviewed: October 29, 2026
This article is for general information and isn't medical advice. Talk to a doctor or pharmacist before starting any supplement.